When Bernie Sanders won New Hampshire by a wide margin, he was understandably excited. “Because of a huge voter turnout — and I say huge,” he said afterward, drawing out the “u" sound in his distinctive Brooklyn accent, “we won.” The turnout overall was not that huge, but Sanders still received more votes than any previous Democrat in the state by a wide margin.

After Nevada, Sanders's worst loss so far, his analysis was different. “What I’ve said over and over again," he said on “Meet the Press,” “we will do well when young people, when working-class people come out. We do not do well when the voter turnout is not large. We did not do as good a job as I had wanted to bring out a large turnout.”

Democratic presidential candidate Bernie Sanders said he is confident of continuing his campaign into Super Tuesday in March, when most of the states elect their party nominee for the White House. (Reuters)

Sanders is correct that his campaign comes down to young voters. Less so working class voters, it seems; in Nevada, Clinton won low-income voters, and Sanders's margin among those earning less than $50,000 a year in Iowa was under 10 points. But among young voters? Sanders is a runaway favorite, earning multiples of Clinton’s support. In Iowa and Nevada, voters under 30 went 6 to 1 for Sanders. In New Hampshire, 5 to 1.

The age split is probably even a more important split than the one on race, in fact. In Nevada entrance polls, younger Hispanic voters backed Sanders heavily, while older Hispanic voters didn’t. The Wall Street Journal reports a similar split among African American voters.

In the two states Sanders lost — Iowa and Nevada — young voters turned out much less versus their share of the population (as of the most recent Census estimates) than in New Hampshire. Those aged 18 to 30 are a smaller percentage of the population in New Hampshire than they are in Iowa or Nevada, but they turned out about as much in this year’s contests. (There are margins of error on these that are not insignificant, but that's not important at this point.)

And look at that support for Sanders! Massive.

The problem — which also happens to be the ongoing, perpetual problem for candidates who bank on the youth vote — is that older voters usually over-perform.

And look at those margins for Hillary Clinton.

We’ve noted repeatedly that young people simply don’t turn out to vote as much as older voters. That overlaps a bit with Sanders’s “working class” comment; income, education level and age are all overlapping groups which tend to vote less frequently. Age alone:

Hillary Clinton won Nevada in large part because of her overwhelming support from black voters. She won Iowa because older voters turned out more than they did in 2008 and because younger voters turned out less. What’s more, there’s not much evidence that Sanders’s younger voters are more motivated to turn out for him than are Clinton’s older ones.

This is why campaigns that need younger voters in order to win often don’t. Younger voters — who move more often, work weirder hours and aren’t in the habit of voting — simply don’t vote as much. Which, Bernie Sanders said, is why Hillary Clinton beat him on Saturday.

Bernie Sanders enjoys strong support among young voters, but they'll need to turn out at the polls if he wants to win the Democratic nomination. (Peter Stevenson/The Washington Post)